The Antibacterial Activity of a New Polymeric Local Drug Delivery System against an In-vitro Multispecies Pathogens Associated with Periodontitis

Introduction: The purpose of this study was to evaluate the antibacterial properties of a local delivery system using an in vitro multispecies bacterial model associated with periodontal diseases. Materials and Methods:Minimum inhibitory concentration (MIC) of effective drugs in periodontitis, doxycycline and metronidazole against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Provetella intermedia and their multispecies mixture was determined. Drug-loaded polymeric films based on polycaprolactone and alginic acid with four different weight percentages for each drug were fabricated by solvent casting method. Antimicrobial properties of polymeric films against bacterial mixture were evaluated using disc agar diffusion test (DAD), planktonic cell count and biofilm formation. Data were analyzed by one-way analysis of variance (ANOVA), followed by a post-hoc Tukey test. Results: MIC of metronidazole for A. actinomycetemcomitans, P. gingivalis, and P. intermedia strains were found 64, 2 and 0.25 μg/mL, while MIC of doxycycline were found 4, 0.25, and 4 μg/mL, respectively. DAD test exhibited that all polymeric films had an obvious inhibitory effect on bacterial mixture ranging from 16 to 30 mm. Drug-loaded polymeric films against the above multispecies bacterial model significantly reduced both planktonic cell count and biofilm formation compared to control (p < 0.05). Our data showed a reduction of ≥ 3 log CFU/mL in all treated groups until the end of experiment in 72h, showing the bactericidal efficacy. Conclusion:All polymeric films followed an accepted antibiofilm activity and bactericidal action. Doxycycline-loaded polymeric films were more effective on multispecies bacteria, inhibiting both planktonic and biofilm growth at relatively low concentrations.